fft example.c

来自「自己编的数值计算方法的c语言实现源程序。」· C语言 代码 · 共 43 行

	#include"stdio.h"
	#include"fft.c"
	
	void main(void)
	{
		double y[256],yi[256];
		double t=0;
		double pace=atan(1.0)/32;
		int i;

		FILE *fp;
		if(( fp=fopen("fft example.txt","w"))==NULL)
		{	printf("cannot open file 'fft example.txt'!\n");
		exit(0);
		}
		
		for(i=0;i<256;i++)
		{
			t+=pace;
			y[i]=exp(-cos(t)*cos(t))*(sin(2*t)+2*cos(4*t)+0.4*sin(t)*sin(50*t));
			yi[i]=0;
		}
		for(i=0;i<256;i++)
		{	fprintf(fp,"%lf ",y[i]);
		}
		fprintf(fp,"\n\n");
		
		fft(y,yi,256,1);
		for(i=5;i<251;i++)
		{	y[i]=0; 
		}  
		fft(y,yi,256,-1);
		
		for(i=0;i<256;i++)
		{	fprintf(fp,"%lf ",y[i]);
		}
		fprintf(fp,"\n\n");
		for(i=0;i<256;i++)
		{	fprintf(fp,"%lf ",yi[i]);
		}
		
		fclose(fp);
}